1. Field of the Invention
The invention relates to a cooling system for an electrically rotating machine, in particular for a gearless three-phase asychronous high-speed motor, which has cooling conduits between the bundle of laminations and the housing as well as connections in the housing that are for the supply and discharge of the coolant.
2. Discussion of Background Information
High-speed motors with speeds greater than 10,000 rpm are a special subject in the motor field. The technical problems are enormous at such high speeds and increase exponentially with increasing speed and/or power.
The state of the art for this kind of high-speed machines, with speeds of up to 18,000 rpm and powers below 100 kW is the direct current technology. However, due to the enormous wear and tear on the brushes in long term operation, this technology is connected with high costs.
The control of critical whirling speed is one of the key aims in the development of high-speed motors. The smaller the bearing spacing is on the motor shaft, the easier it is to control the critical whirling speed. All other structural requirements must be subordinated to the demand for a motor shaft that is as short as possible. With the shortening of the bearing spacing, though, the motor becomes more compact and as a result, the cooling problems become disproportionately greater.
In actual practice, the structural length is normally determined based on the calculation of the critical whirling speed and the attempt is made to carry away the dissipated heat by means of particular steps. As a result, it is inevitable that the component temperature rises and one approaches the use limit of the materials employed.